title: Chitosan-coated magnetic nanoparticles prepared in one step by reverse microemulsion precipitation.
abstract: Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 °C and 80 °C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ≈4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle size. The chitosan coating on nanoparticles was inferred from Fourier transform infrared spectrometry measurements; furthermore, the carbon concentration in the nanoparticles allowed an estimation of chitosan content in CMNP of 6%-7%. CMNP exhibit a superparamagnetic behavior with relatively high final magnetization values (≈49-53 emu/g) at 20 kOe and room temperature, probably due to a higher magnetite content in the mixture of magnetic nanoparticles. In addition, a slight direct effect of precipitation temperature on magnetization was identified, which was ascribed to a possible higher degree of nanoparticles crystallinity as temperature at which they are obtained increases. Tested for Pb2+ removal from a Pb(NO3)2 aqueous solution, CMNP showed a recovery efficacy of 100%, which makes them attractive for using in heavy metals ion removal from waste water.
authors.affiliation: Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna 140, Saltillo 25294, Coahuila, Mexico. guillermo.lopez@ciqa.edu.mx.
authors.forename: Raúl G
authors.initials: RG
authors.lastname: López
authors.forename: María G
authors.initials: MG
authors.lastname: Pineda
authors.forename: Gilberto
authors.initials: G
authors.lastname: Hurtado
authors.forename: Ramón Díaz de
authors.initials: RD
authors.lastname: León
authors.forename: Salvador
authors.initials: S
authors.lastname: Fernández
authors.forename: Hened
authors.initials: H
authors.lastname: Saade
authors.forename: Darío
authors.initials: D
authors.lastname: Bueno
mesh_terms: D011232:Chemical Precipitation; D048271:Chitosan / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry*; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D008280:Magnetics / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013696:Temperature
chemical_list: D004655:Emulsions; D048271:Chitosan; D052203:Ferrosoferric Oxide